Dear Dr. Universe: What is venom? -Callum, 9

A lot of different animals, like wasps, spiders, snakes, jellyfish, and scorpions, make venom. Animals like the cone snail, the blue-ringed octopus, and centipedes do, too.

Venom is a mixture of different proteins that can be very toxic to animals. While humans don’t make venom, they do carry around proteins. Proteins called keratin are the building blocks of your hair and nails. The red protein hemoglobin in your blood helps deliver oxygen around your body.

Venom tries to disrupt the systems in our body that help keep us alive, said my friend Mark Margres. He’s a researcher who studied at Washington State University and now works at Clemson University.

In his work as a scientist, he’s also studied the venomous eastern diamondback rattlesnake. It is the largest of the 32 species in the rattlesnake family. It’s about four or five feet long. Snake venom is one of the kinds of venom scientists know the most about. Margres has collected thousands of samples of rattlesnake venom and he said proteins in the venom can do different things.

The proteins might prevent blood from clotting. They might create a drop in blood pressure. They might even stop the heart.

In the eastern diamondback rattlesnakes, some toxins can actually paralyze a mouse’s legs. But these toxins only paralyze the legs for about 30 minutes, then the mice can move around again. Some of the rattlesnake’s toxins will actually kill the prey. Then there are other toxins that help the snake digest its food.

Margres said that when an animal gets bit and venom enters the body, a lot of people think the venom travels through the blood. But it actually takes a different path.

The venom travels through a network of organs and tissues that are usually supposed to help an animal get rid of toxins and other unwanted invaders. It’s called the lymphatic system. When venom enters this system, it can spread all around the body.

It’s also a myth that you can suck out venom to keep it from spreading. Once the venom is in the body we can’t stop it without something like a medication called anti-venom.

Margres said that snakes can control how much venom they inject into an animal and sometimes make a “dry bite” using just their teeth— no venom.

“We are not exactly sure how or why they choose to do what they do,” Margres said.

Who knows? Maybe one day you can study venomous animals on our planet to help us learn more about these creatures, their defense mechanisms, and even how we can use venom to help make medications.

Margres adds that snake bites are often a sign that an animal was feeling threatened and needed to take action to protect itself. It turns out, rattlesnakes actually can’t eat without using their venom—they need it to kill their prey. Otherwise, they go hungry. They only bite as a last resort and don’t want to waste their venom.